<?php

/*!
 * cssmin.php v2.4.8-4
 * Author: Tubal Martin - http://tubalmartin.me/
 * Repo: https://github.com/tubalmartin/YUI-CSS-compressor-PHP-port
 *
 * This is a PHP port of the CSS minification tool distributed with YUICompressor,
 * itself a port of the cssmin utility by Isaac Schlueter - http://foohack.com/
 * Permission is hereby granted to use the PHP version under the same
 * conditions as the YUICompressor.
 */

/*!
 * YUI Compressor
 * http://developer.yahoo.com/yui/compressor/
 * Author: Julien Lecomte - http://www.julienlecomte.net/
 * Copyright (c) 2013 Yahoo! Inc. All rights reserved.
 * The copyrights embodied in the content of this file are licensed
 * by Yahoo! Inc. under the BSD (revised) open source license.
 */

class CSSmin {
	const NL = '___YUICSSMIN_PRESERVED_NL___';
	const TOKEN = '___YUICSSMIN_PRESERVED_TOKEN_';
	const COMMENT = '___YUICSSMIN_PRESERVE_CANDIDATE_COMMENT_';
	const CLASSCOLON = '___YUICSSMIN_PSEUDOCLASSCOLON___';
	const QUERY_FRACTION = '___YUICSSMIN_QUERY_FRACTION___';

	private $comments;
	private $preserved_tokens;
	private $memory_limit;
	private $max_execution_time;
	private $pcre_backtrack_limit;
	private $pcre_recursion_limit;
	private $raise_php_limits;

	/**
	 * @param bool|int $raise_php_limits
	 * If true, PHP settings will be raised if needed
	 */
	public function __construct( $raise_php_limits = true ) {
		// Set suggested PHP limits
		$this->memory_limit         = 128 * 1048576; // 128MB in bytes
		$this->max_execution_time   = 60; // 1 min
		$this->pcre_backtrack_limit = 1000 * 1000;
		$this->pcre_recursion_limit = 500 * 1000;

		$this->raise_php_limits = (bool) $raise_php_limits;
	}

	/**
	 * Minify a string of CSS
	 *
	 * @param string $css
	 * @param int|bool $linebreak_pos
	 *
	 * @return string
	 */
	public function run( $css = '', $linebreak_pos = false ) {
		if ( empty( $css ) ) {
			return '';
		}

		if ( $this->raise_php_limits ) {
			$this->do_raise_php_limits();
		}

		$this->comments         = array();
		$this->preserved_tokens = array();

		$start_index = 0;
		$length      = strlen( $css );

		$css = $this->extract_data_urls( $css );

		// collect all comment blocks...
		while ( ( $start_index = $this->index_of( $css, '/*', $start_index ) ) >= 0 ) {
			$end_index = $this->index_of( $css, '*/', $start_index + 2 );
			if ( $end_index < 0 ) {
				$end_index = $length;
			}
			$comment_found           = $this->str_slice( $css, $start_index + 2, $end_index );
			$this->comments[]        = $comment_found;
			$comment_preserve_string = self::COMMENT . ( count( $this->comments ) - 1 ) . '___';
			$css                     = $this->str_slice( $css, 0, $start_index + 2 ) . $comment_preserve_string . $this->str_slice( $css, $end_index );
			// Set correct start_index: Fixes issue #2528130
			$start_index = $end_index + 2 + strlen( $comment_preserve_string ) - strlen( $comment_found );
		}

		// preserve strings so their content doesn't get accidentally minified
		$css = preg_replace_callback( '/(?:"(?:[^\\\\"]|\\\\.|\\\\)*")|' . "(?:'(?:[^\\\\']|\\\\.|\\\\)*')/S", array(
			$this,
			'replace_string'
		), $css );

		// Let's divide css code in chunks of 5.000 chars aprox.
		// Reason: PHP's PCRE functions like preg_replace have a "backtrack limit"
		// of 100.000 chars by default (php < 5.3.7) so if we're dealing with really
		// long strings and a (sub)pattern matches a number of chars greater than
		// the backtrack limit number (i.e. /(.*)/s) PCRE functions may fail silently
		// returning NULL and $css would be empty.
		$charset          = '';
		$charset_regexp   = '/(@charset)( [^;]+;)/i';
		$css_chunks       = array();
		$css_chunk_length = 5000; // aprox size, not exact
		$start_index      = 0;
		$i                = $css_chunk_length; // save initial iterations
		$l                = strlen( $css );


		// if the number of characters is 5000 or less, do not chunk
		if ( $l <= $css_chunk_length ) {
			$css_chunks[] = $css;
		} else {
			// chunk css code securely
			while ( $i < $l ) {
				$i += 50; // save iterations
				if ( $l - $start_index <= $css_chunk_length || $i >= $l ) {
					$css_chunks[] = $this->str_slice( $css, $start_index );
					break;
				}
				if ( $css[ $i - 1 ] === '}' && $i - $start_index > $css_chunk_length ) {
					// If there are two ending curly braces }} separated or not by spaces,
					// join them in the same chunk (i.e. @media blocks)
					$next_chunk = substr( $css, $i );
					if ( preg_match( '/^\s*\}/', $next_chunk ) ) {
						$i = $i + $this->index_of( $next_chunk, '}' ) + 1;
					}

					$css_chunks[] = $this->str_slice( $css, $start_index, $i );
					$start_index  = $i;
				}
			}
		}

		// Minify each chunk
		for ( $i = 0, $n = count( $css_chunks ); $i < $n; $i ++ ) {
			$css_chunks[ $i ] = $this->minify( $css_chunks[ $i ], $linebreak_pos );
			// Keep the first @charset at-rule found
			if ( empty( $charset ) && preg_match( $charset_regexp, $css_chunks[ $i ], $matches ) ) {
				$charset = strtolower( $matches[1] ) . $matches[2];
			}
			// Delete all @charset at-rules
			$css_chunks[ $i ] = preg_replace( $charset_regexp, '', $css_chunks[ $i ] );
		}

		// Update the first chunk and push the charset to the top of the file.
		$css_chunks[0] = $charset . $css_chunks[0];

		return implode( '', $css_chunks );
	}

	/**
	 * Try to configure PHP to use at least the suggested minimum settings
	 */
	private function do_raise_php_limits() {
		$php_limits = array(
			'memory_limit'         => $this->memory_limit,
			'max_execution_time'   => $this->max_execution_time,
			'pcre.backtrack_limit' => $this->pcre_backtrack_limit,
			'pcre.recursion_limit' => $this->pcre_recursion_limit
		);

		// If current settings are higher respect them.
		foreach ( $php_limits as $name => $suggested ) {
			$current = $this->normalize_int( ini_get( $name ) );
			// memory_limit exception: allow -1 for "no memory limit".
			if ( $current > - 1 && ( $suggested == - 1 || $current < $suggested ) ) {
				ini_set( $name, $suggested );
			}
		}
	}

	/**
	 * Convert strings like "64M" or "30" to int values
	 *
	 * @param mixed $size
	 *
	 * @return int
	 */
	private function normalize_int( $size ) {
		if ( is_string( intval( $size ) ) ) {
			switch ( substr( $size, - 1 ) ) {
				case 'M':
				case 'm':
					return $size * 1048576;
				case 'K':
				case 'k':
					return $size * 1024;
				case 'G':
				case 'g':
					return $size * 1073741824;
			}
		}

		return (int) $size;
	}

	/**
	 * Utility method to replace all data urls with tokens before we start
	 * compressing, to avoid performance issues running some of the subsequent
	 * regexes against large strings chunks.
	 *
	 * @param string $css
	 *
	 * @return string
	 */
	private function extract_data_urls( $css ) {
		// Leave data urls alone to increase parse performance.
		$max_index    = strlen( $css ) - 1;
		$append_index = $index = $last_index = $offset = 0;
		$sb           = array();
		$pattern      = '/url\(\s*(["\']?)data\:/i';

		// Since we need to account for non-base64 data urls, we need to handle
		// ' and ) being part of the data string. Hence switching to indexOf,
		// to determine whether or not we have matching string terminators and
		// handling sb appends directly, instead of using matcher.append* methods.

		while ( preg_match( $pattern, $css, $m, 0, $offset ) ) {
			$index            = $this->index_of( $css, $m[0], $offset );
			$last_index       = $index + strlen( $m[0] );
			$start_index      = $index + 4; // "url(".length()
			$end_index        = $last_index - 1;
			$terminator       = $m[1]; // ', " or empty (not quoted)
			$found_terminator = false;

			if ( strlen( $terminator ) === 0 ) {
				$terminator = ')';
			}

			while ( $found_terminator === false && $end_index + 1 <= $max_index ) {
				$end_index = $this->index_of( $css, $terminator, $end_index + 1 );

				// endIndex == 0 doesn't really apply here
				if ( $end_index > 0 && substr( $css, $end_index - 1, 1 ) !== '\\' ) {
					$found_terminator = true;
					if ( ')' != $terminator ) {
						$end_index = $this->index_of( $css, ')', $end_index );
					}
				}
			}

			// Enough searching, start moving stuff over to the buffer
			$sb[] = $this->str_slice( $css, $append_index, $index );

			if ( $found_terminator ) {
				$token                    = $this->str_slice( $css, $start_index, $end_index );
				$token                    = preg_replace( '/\s+/', '', $token );
				$this->preserved_tokens[] = $token;

				$preserver = 'url(' . self::TOKEN . ( count( $this->preserved_tokens ) - 1 ) . '___)';
				$sb[]      = $preserver;

				$append_index = $end_index + 1;
			} else {
				// No end terminator found, re-add the whole match. Should we throw/warn here?
				$sb[]         = $this->str_slice( $css, $index, $last_index );
				$append_index = $last_index;
			}

			$offset = $last_index;
		}

		$sb[] = $this->str_slice( $css, $append_index );

		return implode( '', $sb );
	}

	/**
	 * PHP port of Javascript's "indexOf" function for strings only
	 * Author: Tubal Martin http://blog.margenn.com
	 *
	 * @param string $haystack
	 * @param string $needle
	 * @param int $offset index (optional)
	 *
	 * @return int
	 */
	private function index_of( $haystack, $needle, $offset = 0 ) {
		$index = strpos( $haystack, $needle, $offset );

		return ( $index !== false ) ? $index : - 1;
	}

	/**
	 * PHP port of Javascript's "slice" function for strings only
	 * Author: Tubal Martin http://blog.margenn.com
	 * Tests: http://margenn.com/tubal/str_slice/
	 *
	 * @param string $str
	 * @param int $start index
	 * @param int|bool $end index (optional)
	 *
	 * @return string
	 */
	private function str_slice( $str, $start = 0, $end = false ) {
		if ( $end !== false && ( $start < 0 || $end <= 0 ) ) {
			$max = strlen( $str );

			if ( $start < 0 ) {
				if ( ( $start = $max + $start ) < 0 ) {
					return '';
				}
			}

			if ( $end < 0 ) {
				if ( ( $end = $max + $end ) < 0 ) {
					return '';
				}
			}

			if ( $end <= $start ) {
				return '';
			}
		}

		$slice = ( $end === false ) ? substr( $str, $start ) : substr( $str, $start, $end - $start );

		return ( $slice === false ) ? '' : $slice;
	}

	/**
	 * Does bulk of the minification
	 *
	 * @param string $css
	 * @param int|bool $linebreak_pos
	 *
	 * @return string
	 */
	private function minify( $css, $linebreak_pos ) {
		// strings are safe, now wrestle the comments
		for ( $i = 0, $max = count( $this->comments ); $i < $max; $i ++ ) {

			$token       = $this->comments[ $i ];
			$placeholder = '/' . self::COMMENT . $i . '___/';

			// ! in the first position of the comment means preserve
			// so push to the preserved tokens keeping the !
			if ( substr( $token, 0, 1 ) === '!' ) {
				$this->preserved_tokens[] = $token;
				$token_tring              = self::TOKEN . ( count( $this->preserved_tokens ) - 1 ) . '___';
				$css                      = preg_replace( $placeholder, $token_tring, $css, 1 );
				// Preserve new lines for /*! important comments
				$css = preg_replace( '/\s*[\n\r\f]+\s*(\/\*' . $token_tring . ')/S', self::NL . '$1', $css );
				$css = preg_replace( '/(' . $token_tring . '\*\/)\s*[\n\r\f]+\s*/', '$1' . self::NL, $css );
				continue;
			}

			// \ in the last position looks like hack for Mac/IE5
			// shorten that to /*\*/ and the next one to /**/
			if ( substr( $token, ( strlen( $token ) - 1 ), 1 ) === '\\' ) {
				$this->preserved_tokens[] = '\\';
				$css                      = preg_replace( $placeholder, self::TOKEN . ( count( $this->preserved_tokens ) - 1 ) . '___', $css, 1 );
				$i                        = $i + 1; // attn: advancing the loop
				$this->preserved_tokens[] = '';
				$css                      = preg_replace( '/' . self::COMMENT . $i . '___/', self::TOKEN . ( count( $this->preserved_tokens ) - 1 ) . '___', $css, 1 );
				continue;
			}

			// keep empty comments after child selectors (IE7 hack)
			// e.g. html >/**/ body
			if ( strlen( $token ) === 0 ) {
				$start_index = $this->index_of( $css, $this->str_slice( $placeholder, 1, - 1 ) );
				if ( $start_index > 2 ) {
					if ( substr( $css, $start_index - 3, 1 ) === '>' ) {
						$this->preserved_tokens[] = '';
						$css                      = preg_replace( $placeholder, self::TOKEN . ( count( $this->preserved_tokens ) - 1 ) . '___', $css, 1 );
					}
				}
			}

			// in all other cases kill the comment
			$css = preg_replace( '/\/\*' . $this->str_slice( $placeholder, 1, - 1 ) . '\*\//', '', $css, 1 );
		}


		// Normalize all whitespace strings to single spaces. Easier to work with that way.
		$css = preg_replace( '/\s+/', ' ', $css );

		// Fix IE7 issue on matrix filters which browser accept whitespaces between Matrix parameters
		$css = preg_replace_callback( '/\s*filter\:\s*progid:DXImageTransform\.Microsoft\.Matrix\(([^\)]+)\)/', array(
			$this,
			'preserve_old_IE_specific_matrix_definition'
		), $css );

		// Shorten & preserve calculations calc(...) since spaces are important
		$css = preg_replace_callback( '/calc(\(((?:[^\(\)]+|(?1))*)\))/i', array( $this, 'replace_calc' ), $css );

		// Replace positive sign from numbers preceded by : or a white-space before the leading space is removed
		// +1.2em to 1.2em, +.8px to .8px, +2% to 2%
		$css = preg_replace( '/((?<!\\\\)\:|\s)\+(\.?\d+)/S', '$1$2', $css );

		// Remove leading zeros from integer and float numbers preceded by : or a white-space
		// 000.6 to .6, -0.8 to -.8, 0050 to 50, -01.05 to -1.05
		$css = preg_replace( '/((?<!\\\\)\:|\s)(\-?)0+(\.?\d+)/S', '$1$2$3', $css );

		// Remove trailing zeros from float numbers preceded by : or a white-space
		// -6.0100em to -6.01em, .0100 to .01, 1.200px to 1.2px
		$css = preg_replace( '/((?<!\\\\)\:|\s)(\-?)(\d?\.\d+?)0+([^\d])/S', '$1$2$3$4', $css );

		// Remove trailing .0 -> -9.0 to -9
		$css = preg_replace( '/((?<!\\\\)\:|\s)(\-?\d+)\.0([^\d])/S', '$1$2$3', $css );

		// Replace 0 length numbers with 0
		$css = preg_replace( '/((?<!\\\\)\:|\s)\-?\.?0+([^\d])/S', '${1}0$2', $css );

		// Remove the spaces before the things that should not have spaces before them.
		// But, be careful not to turn "p :link {...}" into "p:link{...}"
		// Swap out any pseudo-class colons with the token, and then swap back.
		$css = preg_replace_callback( '/(?:^|\})[^\{]*\s+\:/', array( $this, 'replace_colon' ), $css );

		// Remove spaces before the things that should not have spaces before them.
		$css = preg_replace( '/\s+([\!\{\}\;\:\>\+\(\)\]\~\=,])/', '$1', $css );

		// Restore spaces for !important
		$css = preg_replace( '/\!important/i', ' !important', $css );

		// bring back the colon
		$css = preg_replace( '/' . self::CLASSCOLON . '/', ':', $css );

		// retain space for special IE6 cases
		$css = preg_replace_callback( '/\:first\-(line|letter)(\{|,)/i', array(
			$this,
			'lowercase_pseudo_first'
		), $css );

		// no space after the end of a preserved comment
		$css = preg_replace( '/\*\/ /', '*/', $css );

		// lowercase some popular @directives
		$css = preg_replace_callback( '/@(font-face|import|(?:-(?:atsc|khtml|moz|ms|o|wap|webkit)-)?keyframe|media|page|namespace)/i', array(
			$this,
			'lowercase_directives'
		), $css );

		// lowercase some more common pseudo-elements
		$css = preg_replace_callback( '/:(active|after|before|checked|disabled|empty|enabled|first-(?:child|of-type)|focus|hover|last-(?:child|of-type)|link|only-(?:child|of-type)|root|:selection|target|visited)/i', array(
			$this,
			'lowercase_pseudo_elements'
		), $css );

		// lowercase some more common functions
		$css = preg_replace_callback( '/:(lang|not|nth-child|nth-last-child|nth-last-of-type|nth-of-type|(?:-(?:moz|webkit)-)?any)\(/i', array(
			$this,
			'lowercase_common_functions'
		), $css );

		// lower case some common function that can be values
		// NOTE: rgb() isn't useful as we replace with #hex later, as well as and() is already done for us
		$css = preg_replace_callback( '/([:,\( ]\s*)(attr|color-stop|from|rgba|to|url|(?:-(?:atsc|khtml|moz|ms|o|wap|webkit)-)?(?:calc|max|min|(?:repeating-)?(?:linear|radial)-gradient)|-webkit-gradient)/iS', array(
			$this,
			'lowercase_common_functions_values'
		), $css );

		// Put the space back in some cases, to support stuff like
		// @media screen and (-webkit-min-device-pixel-ratio:0){
		$css = preg_replace( '/\band\(/i', 'and (', $css );

		// Remove the spaces after the things that should not have spaces after them.
		$css = preg_replace( '/([\!\{\}\:;\>\+\(\[\~\=,])\s+/S', '$1', $css );

		// remove unnecessary semicolons
		$css = preg_replace( '/;+\}/', '}', $css );

		// Fix for issue: #2528146
		// Restore semicolon if the last property is prefixed with a `*` (lte IE7 hack)
		// to avoid issues on Symbian S60 3.x browsers.
		$css = preg_replace( '/(\*[a-z0-9\-]+\s*\:[^;\}]+)(\})/', '$1;$2', $css );

		// Replace 0 <length> and 0 <percentage> values with 0.
		// <length> data type: https://developer.mozilla.org/en-US/docs/Web/CSS/length
		// <percentage> data type: https://developer.mozilla.org/en-US/docs/Web/CSS/percentage
		$css = preg_replace( '/([^\\\\]\:|\s)0(?:em|ex|ch|rem|vw|vh|vm|vmin|cm|mm|in|px|pt|pc|%)/iS', '${1}0', $css );

		// 0% step in a keyframe? restore the % unit
		$css = preg_replace_callback( '/(@[a-z\-]*?keyframes[^\{]+\{)(.*?)(\}\})/iS', array(
			$this,
			'replace_keyframe_zero'
		), $css );

		// Replace 0 0; or 0 0 0; or 0 0 0 0; with 0.
		$css = preg_replace( '/\:0(?: 0){1,3}(;|\}| \!)/', ':0$1', $css );

		// Fix for issue: #2528142
		// Replace text-shadow:0; with text-shadow:0 0 0;
		$css = preg_replace( '/(text-shadow\:0)(;|\}| \!)/i', '$1 0 0$2', $css );

		// Replace background-position:0; with background-position:0 0;
		// same for transform-origin
		// Changing -webkit-mask-position: 0 0 to just a single 0 will result in the second parameter defaulting to 50% (center)
		$css = preg_replace( '/(background\-position|webkit-mask-position|(?:webkit|moz|o|ms|)\-?transform\-origin)\:0(;|\}| \!)/iS', '$1:0 0$2', $css );

		// Shorten colors from rgb(51,102,153) to #336699, rgb(100%,0%,0%) to #ff0000 (sRGB color space)
		// Shorten colors from hsl(0, 100%, 50%) to #ff0000 (sRGB color space)
		// This makes it more likely that it'll get further compressed in the next step.
		$css = preg_replace_callback( '/rgb\s*\(\s*([0-9,\s\-\.\%]+)\s*\)(.{1})/i', array(
			$this,
			'rgb_to_hex'
		), $css );
		$css = preg_replace_callback( '/hsl\s*\(\s*([0-9,\s\-\.\%]+)\s*\)(.{1})/i', array(
			$this,
			'hsl_to_hex'
		), $css );

		// Shorten colors from #AABBCC to #ABC or short color name.
		$css = $this->compress_hex_colors( $css );

		// border: none to border:0, outline: none to outline:0
		$css = preg_replace( '/(border\-?(?:top|right|bottom|left|)|outline)\:none(;|\}| \!)/iS', '$1:0$2', $css );

		// shorter opacity IE filter
		$css = preg_replace( '/progid\:DXImageTransform\.Microsoft\.Alpha\(Opacity\=/i', 'alpha(opacity=', $css );

		// Find a fraction that is used for Opera's -o-device-pixel-ratio query
		// Add token to add the "\" back in later
		$css = preg_replace( '/\(([a-z\-]+):([0-9]+)\/([0-9]+)\)/i', '($1:$2' . self::QUERY_FRACTION . '$3)', $css );

		// Remove empty rules.
		$css = preg_replace( '/[^\};\{\/]+\{\}/S', '', $css );

		// Add "/" back to fix Opera -o-device-pixel-ratio query
		$css = preg_replace( '/' . self::QUERY_FRACTION . '/', '/', $css );

		// Replace multiple semi-colons in a row by a single one
		// See SF bug #1980989
		$css = preg_replace( '/;;+/', ';', $css );

		// Restore new lines for /*! important comments
		$css = preg_replace( '/' . self::NL . '/', "\n", $css );

		// Lowercase all uppercase properties
		$css = preg_replace_callback( '/(\{|\;)([A-Z\-]+)(\:)/', array( $this, 'lowercase_properties' ), $css );

		// Some source control tools don't like it when files containing lines longer
		// than, say 8000 characters, are checked in. The linebreak option is used in
		// that case to split long lines after a specific column.
		if ( $linebreak_pos !== false && (int) $linebreak_pos >= 0 ) {
			$linebreak_pos = (int) $linebreak_pos;
			$start_index   = $i = 0;
			while ( $i < strlen( $css ) ) {
				$i ++;
				if ( $css[ $i - 1 ] === '}' && $i - $start_index > $linebreak_pos ) {
					$css         = $this->str_slice( $css, 0, $i ) . "\n" . $this->str_slice( $css, $i );
					$start_index = $i;
				}
			}
		}

		// restore preserved comments and strings in reverse order
		for ( $i = count( $this->preserved_tokens ) - 1; $i >= 0; $i -- ) {
			$css = preg_replace( '/' . self::TOKEN . $i . '___/', $this->preserved_tokens[ $i ], $css, 1 );
		}

		// Trim the final string (for any leading or trailing white spaces)
		return trim( $css );
	}

	/**
	 * Utility method to compress hex color values of the form #AABBCC to #ABC or short color name.
	 *
	 * DOES NOT compress CSS ID selectors which match the above pattern (which would break things).
	 * e.g. #AddressForm { ... }
	 *
	 * DOES NOT compress IE filters, which have hex color values (which would break things).
	 * e.g. filter: chroma(color="#FFFFFF");
	 *
	 * DOES NOT compress invalid hex values.
	 * e.g. background-color: #aabbccdd
	 *
	 * @param string $css
	 *
	 * @return string
	 */
	private function compress_hex_colors( $css ) {
		// Look for hex colors inside { ... } (to avoid IDs) and which don't have a =, or a " in front of them (to avoid filters)
		$pattern = '/(\=\s*?["\']?)?#([0-9a-f])([0-9a-f])([0-9a-f])([0-9a-f])([0-9a-f])([0-9a-f])(\}|[^0-9a-f{][^{]*?\})/iS';
		$_index  = $index = $last_index = $offset = 0;
		$sb      = array();
		// See: http://ajaxmin.codeplex.com/wikipage?title=CSS%20Colors
		$short_safe = array(
			'#808080' => 'gray',
			'#008000' => 'green',
			'#800000' => 'maroon',
			'#000080' => 'navy',
			'#808000' => 'olive',
			'#ffa500' => 'orange',
			'#800080' => 'purple',
			'#c0c0c0' => 'silver',
			'#008080' => 'teal',
			'#f00'    => 'red'
		);

		while ( preg_match( $pattern, $css, $m, 0, $offset ) ) {
			$index      = $this->index_of( $css, $m[0], $offset );
			$last_index = $index + strlen( $m[0] );
			$is_filter  = $m[1] !== null && $m[1] !== '';

			$sb[] = $this->str_slice( $css, $_index, $index );

			if ( $is_filter ) {
				// Restore, maintain case, otherwise filter will break
				$sb[] = $m[1] . '#' . $m[2] . $m[3] . $m[4] . $m[5] . $m[6] . $m[7];
			} else {
				if ( strtolower( $m[2] ) == strtolower( $m[3] ) &&
				     strtolower( $m[4] ) == strtolower( $m[5] ) &&
				     strtolower( $m[6] ) == strtolower( $m[7] ) ) {
					// Compress.
					$hex = '#' . strtolower( $m[3] . $m[5] . $m[7] );
				} else {
					// Non compressible color, restore but lower case.
					$hex = '#' . strtolower( $m[2] . $m[3] . $m[4] . $m[5] . $m[6] . $m[7] );
				}
				// replace Hex colors to short safe color names
				$sb[] = array_key_exists( $hex, $short_safe ) ? $short_safe[ $hex ] : $hex;
			}

			$_index = $offset = $last_index - strlen( $m[8] );
		}

		$sb[] = $this->str_slice( $css, $_index );

		return implode( '', $sb );
	}

	/**
	 * Sets the memory limit for this script
	 *
	 * @param int|string $limit
	 */
	public function set_memory_limit( $limit ) {
		$this->memory_limit = $this->normalize_int( $limit );
	}

	/* CALLBACKS
	 * ---------------------------------------------------------------------------------------------
	 */

	/**
	 * Sets the maximum execution time for this script
	 *
	 * @param int|string $seconds
	 */
	public function set_max_execution_time( $seconds ) {
		$this->max_execution_time = (int) $seconds;
	}

	/**
	 * Sets the PCRE backtrack limit for this script
	 *
	 * @param int $limit
	 */
	public function set_pcre_backtrack_limit( $limit ) {
		$this->pcre_backtrack_limit = (int) $limit;
	}

	/**
	 * Sets the PCRE recursion limit for this script
	 *
	 * @param int $limit
	 */
	public function set_pcre_recursion_limit( $limit ) {
		$this->pcre_recursion_limit = (int) $limit;
	}

	private function replace_string( $matches ) {
		$match = $matches[0];
		$quote = substr( $match, 0, 1 );
		// Must use addcslashes in PHP to avoid parsing of backslashes
		$match = addcslashes( $this->str_slice( $match, 1, - 1 ), '\\' );

		// maybe the string contains a comment-like substring?
		// one, maybe more? put'em back then
		if ( ( $pos = $this->index_of( $match, self::COMMENT ) ) >= 0 ) {
			for ( $i = 0, $max = count( $this->comments ); $i < $max; $i ++ ) {
				$match = preg_replace( '/' . self::COMMENT . $i . '___/', $this->comments[ $i ], $match, 1 );
			}
		}

		// minify alpha opacity in filter strings
		$match = preg_replace( '/progid\:DXImageTransform\.Microsoft\.Alpha\(Opacity\=/i', 'alpha(opacity=', $match );

		$this->preserved_tokens[] = $match;

		return $quote . self::TOKEN . ( count( $this->preserved_tokens ) - 1 ) . '___' . $quote;
	}

	private function replace_colon( $matches ) {
		return preg_replace( '/\:/', self::CLASSCOLON, $matches[0] );
	}

	private function replace_calc( $matches ) {
		$this->preserved_tokens[] = trim( preg_replace( '/\s*([\*\/\(\),])\s*/', '$1', $matches[2] ) );

		return 'calc(' . self::TOKEN . ( count( $this->preserved_tokens ) - 1 ) . '___' . ')';
	}

	private function preserve_old_IE_specific_matrix_definition( $matches ) {
		$this->preserved_tokens[] = $matches[1];

		return 'filter:progid:DXImageTransform.Microsoft.Matrix(' . self::TOKEN . ( count( $this->preserved_tokens ) - 1 ) . '___' . ')';
	}

	private function replace_keyframe_zero( $matches ) {
		return $matches[1] . preg_replace( '/0(\{|,[^\)\{]+\{)/', '0%$1', $matches[2] ) . $matches[3];
	}

	private function hsl_to_hex( $matches ) {
		$values = explode( ',', str_replace( '%', '', $matches[1] ) );
		$h      = floatval( $values[0] );
		$s      = floatval( $values[1] );
		$l      = floatval( $values[2] );

		// Wrap and clamp, then fraction!
		$h = ( ( ( $h % 360 ) + 360 ) % 360 ) / 360;
		$s = $this->clamp_number( $s, 0, 100 ) / 100;
		$l = $this->clamp_number( $l, 0, 100 ) / 100;

		if ( $s == 0 ) {
			$r = $g = $b = $this->round_number( 255 * $l );
		} else {
			$v2 = $l < 0.5 ? $l * ( 1 + $s ) : ( $l + $s ) - ( $s * $l );
			$v1 = ( 2 * $l ) - $v2;
			$r  = $this->round_number( 255 * $this->hue_to_rgb( $v1, $v2, $h + ( 1 / 3 ) ) );
			$g  = $this->round_number( 255 * $this->hue_to_rgb( $v1, $v2, $h ) );
			$b  = $this->round_number( 255 * $this->hue_to_rgb( $v1, $v2, $h - ( 1 / 3 ) ) );
		}

		return $this->rgb_to_hex( array( '', $r . ',' . $g . ',' . $b, $matches[2] ) );
	}

	private function clamp_number( $n, $min, $max ) {
		return min( max( $n, $min ), $max );
	}

	private function round_number( $n ) {
		return intval( floor( floatval( $n ) + 0.5 ), 10 );
	}

	private function hue_to_rgb( $v1, $v2, $vh ) {
		$vh = $vh < 0 ? $vh + 1 : ( $vh > 1 ? $vh - 1 : $vh );
		if ( $vh * 6 < 1 ) {
			return $v1 + ( $v2 - $v1 ) * 6 * $vh;
		}
		if ( $vh * 2 < 1 ) {
			return $v2;
		}
		if ( $vh * 3 < 2 ) {
			return $v1 + ( $v2 - $v1 ) * ( ( 2 / 3 ) - $vh ) * 6;
		}

		return $v1;
	}

	private function rgb_to_hex( $matches ) {
		// Support for percentage values rgb(100%, 0%, 45%);
		if ( $this->index_of( $matches[1], '%' ) >= 0 ) {
			$rgbcolors = explode( ',', str_replace( '%', '', $matches[1] ) );
			for ( $i = 0; $i < count( $rgbcolors ); $i ++ ) {
				$rgbcolors[ $i ] = $this->round_number( floatval( $rgbcolors[ $i ] ) * 2.55 );
			}
		} else {
			$rgbcolors = explode( ',', $matches[1] );
		}

		// Values outside the sRGB color space should be clipped (0-255)
		for ( $i = 0; $i < count( $rgbcolors ); $i ++ ) {
			$rgbcolors[ $i ] = $this->clamp_number( intval( $rgbcolors[ $i ], 10 ), 0, 255 );
			$rgbcolors[ $i ] = sprintf( "%02x", $rgbcolors[ $i ] );
		}

		// Fix for issue #2528093
		if ( ! preg_match( '/[\s\,\);\}]/', $matches[2] ) ) {
			$matches[2] = ' ' . $matches[2];
		}

		return '#' . implode( '', $rgbcolors ) . $matches[2];
	}

	/* HELPERS
	 * ---------------------------------------------------------------------------------------------
	 */

	private function lowercase_pseudo_first( $matches ) {
		return ':first-' . strtolower( $matches[1] ) . ' ' . $matches[2];
	}

	private function lowercase_directives( $matches ) {
		return '@' . strtolower( $matches[1] );
	}

	private function lowercase_pseudo_elements( $matches ) {
		return ':' . strtolower( $matches[1] );
	}

	private function lowercase_common_functions( $matches ) {
		return ':' . strtolower( $matches[1] ) . '(';
	}

	private function lowercase_common_functions_values( $matches ) {
		return $matches[1] . strtolower( $matches[2] );
	}

	private function lowercase_properties( $matches ) {
		return $matches[1] . strtolower( $matches[2] ) . $matches[3];
	}
}